Tensioning device

ABSTRACT

Tensioning devices for a record tape fed from a storage spool on a shaft rotatably mounted in a housing. A friction brake acting on the storage spool, comprises a first friction member rotatably mounted on the shaft and urged by a coil spring into contact with a second friction member freely rotatable about the shaft but limited to rotation through only a predetermined angle relative to the storage spool. A coil spring is arranged to exert a torque on the second friction member. This torque is smaller than the frictional torque due to the contact between the first and second friction members on rotation of the storage spool. The predetermined relative rotation between the second friction member and the storage spool which occurs on initial rotation of the shaft ensures that the tensioning device does not inhibit the initial acceleration of the storage spool which is in recording machines.

United States Patent Klimek [4 1 Aug. 8, 1972 [54] TENSIONING DEVICE v Primary ExaminerStanley N. Gilreath [72] Inventor. Norbert Klimek, London, England Atmmey Nolte and None [73] Assignee: English Numbering Machines Limited, London, England [57] ABSTRACT [22] Filed: May 11, 1970 Tensioning devices for a record tape fed from a storage spool on a shaft rotatably mounted in a hous- [21] Appl' 36157 ing. A friction brake acting on the storage spool, comprises a first friction member rotatably mounted on [30] Foreign Application Priority Data the shaft and urged by a coil spring into contact with a second friction member freely rotatable about the May 1969 Great Bmam "24558/69 shaft but limited to rotation through only a predeter- 52] U 8 Cl 242/156 2 mined angle relative to the storage spool. A coil spring [51] hide. "1365b 59/64 is arranged to exert a torque on the second friction member. This torque is smaller than the frictional [58] Field Wham/156 torque due to the contact between the first and second friction members on rotation of the storage spool. The [56] Referenm cued predetermined relative rotation between the second UNITED STATES PATENTS friction member and the storage spool which occurs on initial rotation of the shaft ensures that the tensionl,979,9l4 ll/l934 Tomlin ..242/ 156.2 m device does not inhibit the initial acceleration of l i the storage spool which is in recording machines. 3:41 1:285 11/ 1968 McDonald ..242/I56 X 6 Claim, 2 Drawing Figures PATENTEDAH 8m? 3,682,413

SHEET 2 BF 2 ATTO/QA/B/J TENSIONING DEVICE BACKGROUND OF THE INVENTION.

This invention relates to a tensioning device for a wire or tape or the like fed from a storage spool.

In recording machines in which a tape or wire is fed from a storage spool to a take-up spool, it is desirable to tension the tape or wire so that the feed is uniform.

It is an object of the invention to provide a tensioning device which facilitates such a uniform feed of a tape or wire when adapted to a recording machine.

It is a further object of the invention to provide a tensioning device which does not inhibit the necessary initial acceleration of the storage spool.

SUMMARY OF THE INVENTION.

According to one aspect of the invention there is provided a tensioning device for a wire or tape or the like fed from a storage spool, including a friction brake acting on the storage spool, the friction brake comprising a first friction member rotatable with the storage spool and being urged into contact with a second friction member, the second friction member being rotatable through an only predetermined angle relative to the storage spool, and spring means which exert on the second friction member a torque which is smaller than the frictional torque due to the contact between the first and second friction members on rotation of the storage spool.

Preferably, the first and second members are mounted on a common shaft, said first friction member being rotatable with said shaft and said second friction member being freely rotatable on said shaft.

Preferably, the spring means of the second friction member is fixed at one end to said second friction member, the other end of the spring means being fixed by an anchoring pin to a housing rotatably carrying the shaft.

Preferably, the first friction member is urged by spring means and the pressure exerted by the spring means for the first friction member is adjustable.

In both the aforegoing constructions, it is preferably for each friction member to have a flat surface, the flat surfaces contacting each other. Advantageously, one of the friction members is of stainless steel and the other friction member is of teflon.

The tensioning device is particularly suitable for tensioning a tape or wire while travelling from a storagespool to a taken-up spool. In this case, the storage spool is carried by the shaft in such a manner that the shaft rotates with the storage spool and thereby brakes the tape when drawn from the storage spool. Thetape may be a tape of a sound recording or reproducing device. Accordingly, the invention is intended to embrace a tape or the like recording or reproducing device when comprising a tensioning device as hereinbefore defined.

BRIEF DESCRIPTION OF THE DRAWINGS.

An embodiment of the invention will now be described, by way of example only, with reference to the accompany drawings, in which:

FIG. 1 shows a sectional elevation of part of a recording machine employing a tape and tensioning device according to the invention; and

FIG. 2 shows a section taken on the line XX of FIG. 1.

DETAILED DESCRIPTION OF THE- EMBODIMENT.

In the specific embodiment of the invention shown in FIGS. 1 and 2, a storage spool 1 for a tape is mounted on a rotatable shaft 2 so as to be rotatable with the shaft. The shaft 2 is rotatably mounted at 24 and 25 in a casing 3 and the spool 1 is positioned relative to one end of the shaft 2 by a bearing 23. A pin 31 on a flange 32 of the shaft engages a cooperating hole in the reel 1 to key the reel 1 to the shaft 2. The shaft 2 carries a first friction member 4 having a fiat surface 5 perpendicular to the shaft 2 and being rotatable relatively to the shaft 2. The first member 4 carries a coiled spring 7 one end of which 8 is anchored to the member, the other end of the spring 9 being anchored to the casing by means of an anchoring pin 10. The first member 4 is preferably made of stainless steel. A stationary pin 11 engages an arcuate elongated groove or hole 12 in the first member 4 so that normally, under the action of the coiled spring 7, the pin 11 abuts against an end 13 of the elongated groove or hole. When, however, a torque is exerted on the first member 4 in the appropriate sense the first member 4 is rotated against the action of the coiled spring 7 until the pin abuts against the opposite end 14 of the elongated groove or hole 12.

A second flat surface 15 perpendicular to the shaft 2 of a second member 16 abuts against the flat surface 5 of the first member 4. The second member 16 comprises a component which has the flat surface and is preferably made of teflon. The two flat surfaces 5, 15 of the two members 4, 16 are abutting against each other. The teflon member 16 is carried by an annular carrier member 17 mounted on and rotatable with a bushing 18 keyed at 26 to the shaft 2. The member 17 is slidable in the axial direction of the bushing 18. The bushing 18 is in part externally screw-threaded at 19 its screwthreads being engaged by screw-threads of an adjusting nut 20 forming a shoulder on the bushing 18. Between the shoulder and the carrier member 17a compression spring 21 is provided which urges the carrier member 17 towards and presses therewith the second friction member 16 against the first friction member 4, the friction between both members being adjustable by rotating the nut 20.

When inuse a tape is drawn from the storage spool l by ataken-up spool (not shown), the storage spool 1 and thereby the shaft 2 and the second member 16 are rotated. Such rotau'on causes the first member 4 initially to turn against the action of the coiled spring 7 carried thereby so that the stationary pin disengages the end 13 of the arcuate groove or hole 12 and abuts against the other end 14 of the arcuate groove or hole 12 whereupon the first member 4 remains stationary. The second member 16 rotates with the shaft 2 relative to the first member 4 while the flat surfaces 5, 15 of the two members 4, 16 are in frictional engagement with each other. The friction between the flat surface 5, 15 of the two members 4, 16 is adjustable by suitably tuming the nut 20 and thereby setting the compression spring 21 which forces the second member 16 against the first member 4. t

The torque due to the spring 7 acting on the member 4 is less than the frictional torque between the members 4, 16 on rotation of the shaft. The tensioning device has the advantage that the friction brake does not inhibit the necessary initial acceleration of the storage spool.

I claim:

1. A device for tensioning a wire or tape or the like fed from a storage spool, comprising a housing rotatable means for supporting the storage spool for rotation relative to the housing, a friction brake for acting on the supporting means, the friction brake including, a first friction member supported by the housing and rotatable relative to the housing with the supporting means, a second frictional member rotatably supported on the housing, means limiting the rotation of the second frictional member to a predetermined angle relative to the housing, resilient meansfor urging the first friction member into contact with the second fric- 2. A tensioning device as defined in claim 1, said storage spool supporting means including a shaft rotatably carried in the housing on which the first and second members are mounted, said first friction member being rotatable with said shaft and said second friction member being freely rotatable on said shaft.

3. A tensioning device as defined in claim 2 further comprising an anchoring pin secured to the housing, the spring means of the second friction member being fixed at one end to said second friction member, the other end of the spring means being fixed by the anchoring pin to the housing.

4. A tensioning device as defined in claim 1, further including threaded means for adjusting the pressure exerted by the resilient means on the first friction member. I

5. A tensioning device as defined in claim 1, wherein each friction member has a flat surface, the flat surfaces of the two friction members contacting each tion member, and spring means which exert on the 20 othersecond friction member a torque which is smaller than the frictional torque due to the contact between the first and second friction members on said rotation of said supporting means.

6. A tensioning device-as defined in claim 1, wherein one of the friction members is of stainless steel'and the other friction member is of teflon. 

1. A device for tensioning a wire or tape or the like fed from a storage spool, comprising a housing rotatable means for supporting the storage spool for rotation relative to the housing, a friction brake for acting on the supporting means, the friction brake including, a first friction member supported by the housing and rotatable relative to the housing with the supporting means, a second frictional member rotatably supported on the housing, means limiting the rotation of the second frictional member to a predetermined angle relative to the housing, resilient means for urging the first friction member into contact with the second friction member, and spring means which exert on the second friction member a torque which is smaller than the frictional torque due to the contact between the first and second friction members on said rotation of said supporting means.
 2. A tensioning device as defined in claim 1, said storage spool supporting means including a shaft rotatably carried in the housing on which the first and second members are mounted, said first friction member being rotatable with said shaft and said second friction member being freely rotatable on said shaft.
 3. A tensioning device as defined in claim 2 further comprising an anchoring pin secured to the housing, the spring means of the second friction member being fixed at one end to said second friction member, the other end of the spring means being fixed by the anchoring pin to the housing.
 4. A tensioning device as defined in claim 1, further including threaded means for adjusting the pressure exerted by the resilient means on the first friction member.
 5. A tensioning device as defined in claim 1, wherein each friction member has a flat surface, the flat surfaces of the two friction members contacting each other.
 6. A tensioning device as defined in claim 1, wherein one of the friction members is of stainless steel and the other friction member is of teflon. 